Resolving Objects in Deserialization

Resolving Objects in Deserialization

Customer has send the data as serialized object to us, where as I am not interested in all the data or the class which serialized, or I have to create a class in which I can add aditional data in it.

We could do this operation by fetching the object and handing over to some method to create a new Object from it. It is painstaking job, and will not produce nice implmentation approach

We can achive resolving object by creating sub-class for ObjectInputStream with overriding method resolveObject(Object). In this method, we can do our business related sutff and get the objected wanted while deserializing

Example

I have created sub-class MyObjectInputStream from ObjectInputStream and override the resolve method. Note: resolveObject() method will not be called until unless the resolveObject flag set to true by calling method enableResolveObject(true);. I am setting this value true in constructor of the MyObjectInputStream class.

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
public class DeserializeTest {

public static class EmployeeBean implements Serializable
{
 String name;
 String designation;
}

private static class MyObjectInputStream extends ObjectInputStream
{
 public MyObjectInputStream(InputStream in) throws IOException {
  super(in);
  enableResolveObject(true);
 }
 
 @Override
 protected Object resolveObject(Object obj) throws IOException {
  if (obj instanceof EmployeeBean) {
   EmployeeBean new_name = (EmployeeBean) obj;
   StringBuffer sb=new StringBuffer();
   sb.append(new_name.name);
   sb.append(" ");
   sb.append(new_name.designation);
   return sb;
  }
  return super.resolveObject(obj);
 }
}

/**
 * @param args
 */
public static void main(String[] args) throws Exception{
 EmployeeBean emp=new EmployeeBean();
 emp.name = "Krishna";
 emp.designation="PMTS";
 ByteArrayOutputStream bos=new ByteArrayOutputStream();
 ObjectOutputStream out= new ObjectOutputStream(bos);
 out.writeObject(emp);
 
 ByteArrayInputStream bis=new ByteArrayInputStream(bos.toByteArray());
 MyObjectInputStream in= new MyObjectInputStream(bis);
 Object obj=in.readObject();
 System.out.println(obj);
}
}

The Output will be like below

Krishna PMTS

In the above program comment enableResolveObject(true); line and try, the output will be the Object reference of EmployeeBeen; Something like below

ObjectStreamClassTest$EmployeeBean@10b30a7

Note: Playing with ObjectInputStream ,ObjectOutputStream, and ObjectStreamClass, we can do lot and control the content of serialized stream.